Humpback whales frolicking amid Fleet Week, America’s Cup

The boaters and seamen converging on San Francisco Bay this weekend for Fleet Week and the America’s Cup could very well come up against large obstacles — humpback whales.

The whales have been spotted over the past two weeks gallivanting just outside the Golden Gate and, in several cases, venturing inside the bay, raising concerns that there could be a collision.

The National Oceanic and Atmospheric Administration issued a warning to all boaters, ship’s captains, para-sailors, paddlers and other water recreationists to watch out for whales and other large marine mammals this weekend.

The leviathans visit the Gulf of the Farallones National Marine Sanctuary off San Francisco to feed every summer and fall, but one group of humpbacks has been hanging out very close to the mouth of San Francisco Bay, where much of this weekend’s shipping activity is scheduled to occur.

Ship strikes and feeding disruptions are one reason marine biologists believe some whale species, including humpbacks, have yet to fully recover from the rampant whaling that depleted their numbers the past two centuries. Hitting a whale isn’t particularly good for boaters either, marine sanctuary officials said. Such strikes can severely damage a boat and cause serious injury.

Humpback whales, which are listed as endangered under the Endangered Species Act, are known for their complex vocalizations that sound like singing and for their acrobatic breaching, where they lift almost their entire bodies out of the water and splash down. The cetaceans aren’t the only large fish-like creatures plying bay waters right now. Bottlenose dolphins, sea lions, seals and harbor porpoises, often with young calves, are also regularly seen in San Francisco Bay.

Boaters are being asked to watch out for whale spouting, which looks like a puff of smoke about 10 to 15 feet high. They should not approach within 300 feet of a whale, cut across its path, make sudden speed or directional changes or get between a whale and her calf.

Mariners should report collisions and sightings of injured or dead whales to NOAA at 877-767-9425 or to the U.S. Coast Guard on VHF-FM Channel 16 or by calling 562-506-4315.